1. Field of the Invention
This invention relates to an apparatus for cooling integrated circuit chips and, in particular, to a thermal conduction module and a method of adjustment and assembly thereof.
2. Description of Related Art
Integrated circuit chips mounted in an array on substrates present special cooling difficulties. While chip size has increased over the years and power usage is more efficient than in the past, work is still needed on cooling systems and methods to remove the relatively high density power dissipated by the chips. The prior art is replete with different types of thermal conduction modules (TCMs) designed to enclose and cool integrated circuit chips mounted on ceramic-glass substrates. In some instances, the TCMs utilize liquid coolants to cool the chips, such as those described in U.S. Pat. Nos. 5,239,200, 5,294,830 and 5,177,667, issued to the assignee of this application. Another approach to cooling has been described in U.S. Pat. No. 4,500,945, also assigned to the assignee of this application, by the use of pistons contacting the chips within the TCMs to remove heat.
A further approach in cooling chips in TCMs has been to utilize a thermally conductive medium, such as high thermal conductivity pastes, between the top of the integrated circuit chip mounted on the substrate and the lower surface of the cover plate facing the substrate. An example of the useful, stable, high solid content, high thermal conductivity paste is disclosed in U.S. Pat. No. 5,098,609. This compound can be applied as a thin film between the top of the chip and the lower surface of the cover of the TCM. In order to properly control the amount of heat removed from the integrated circuit chip, it is desirable to determine a gap of a specified and desired fixed distance between the top of the chip and the lower surface of the cover, and to fill that space completely with the thermally conductive medium such as the aforementioned paste.
Prior art methods of setting the proper gap between the top surface of the chip and the lower surface of the cover have utilized an integral spacer within the thermal conduction module to control the size of the gap. This spacer is normally integral with the cover plate and extends around the periphery of the area of the substrate on which the integrated surface chips are mounted.
Glass ceramics which are normally used as substrate materials for the integrated circuit chips are brittle and easy to break, and must be handled with care. The substrates are normally mounted in a base plate of the TCM which encompasses the edges of the substrate. The cover plate is normally secured to this base plate surrounding the substrate following assembly of the TCM. It has been found that the use of the integral spacer in the TCM can contribute to breakage of the glass ceramic substrates when the cover plate is fastened too tightly to the base plate. This has been found to occur because the integral spacer transfers force directly to the substrate when the fasteners, typically screws or bolts around the periphery of the cover plate, are tightened down to the base plate. The substrate, which is contained within the base plate by a lip extending within its periphery, is then subject to excessive and uneven forces from the spacer which may not be in direct line with the lip of the base plate. The application of excessive force to the fasteners will then tend to break the substrates near the lip of the base plates. Because parallelism of the lower surface of the cover plate and the tops of the integrated surface chips must be maintained in all assembled parts, an even distribution force must be applied around the periphery of the thermal conduction module.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a thermal conduction module which may be assembled with a controlled gap between the lower surface of the cover plate and the upper surface of the integrated circuit chip without causing excessive force and breakage to the chip substrate, whereby a desired thermally conductive medium may be applied between the chip and the cover plate to effect controlled heat removal and cooling of the chip.
It is another object of the present invention to provide a method of assembling a thermal conduction module which reduces the possibility of breakage of the chip substrate while maintaining a controlled gap between the cover plate and the top surface of the integrated circuit chips for insertion of a thermally conductive medium.
A further object of the invention is to provide a thermal conduction module in which the cover plate may be secured to the base plate with higher loading on the fasteners with a reduced possibility of damage to the chip substrate.
It is yet another object of the present invention to provide an apparatus for cooling integrated circuit chips mounted on a substrate by providing an adjustable spacer between the apparatus cover plate and base plate which does not bear directly on the substrate.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The above and other objects and advantages, which will be apparent to one of skill in the art, are achieved in the present invention which is directed to, in a first aspect, a thermal conduction module assembly kit comprising a base having top and bottom surfaces and being adapted to receive a substrate on its top surface. The substrate is adapted to receive at least one integrated circuit having top and bottom surfaces. The thermal conduction module assembly kit also includes a cover having top and bottom surfaces and an outer edge surface. The cover is adapted to be disposed over the substrate. The integrated circuit is positioned between the bottom surface of the cover and the top surface of the substrate. Further, a removable spacer member has a definable vertical dimension and is positioned between the bottom surface of the cover and the top surface of the integrated circuit. A positioning member has top, bottom, and side surfaces. The side surface of the positioning member situated adjacent to and being affixable to, the outer edge surface of the cover; and the bottom surface of the positioning member is contactable with the top surface of the substrate. The positioning member is slidable along the affixable side surface with respect to the outer edge surface of the cover, to contact the top surface of the substrate and maintain a specified vertical dimension between the bottom surface of the cover and the top surface of the integrated circuit; the specified vertical dimension is defined by the vertical dimension of the removable spacer member.
In a related aspect, the thermal conduction module assembly kit has the bottom surface of the cover and the top surface of the integrated circuit defining a gap having the specified vertical dimension when the affixable side surface of the positioning member is affixed to the outer edge surface of the cover, and the removable space member is removed. The gap is substantially filled with a thermally conductive medium.
In another aspect, the present invention provides a thermal conduction module assembly kit comprising a base having top and bottom surfaces, and a substrate having top and bottom surfaces. The bottom surface of the substrate is adapted to be situated on the top surface of the base. At least one integrated circuit has top and bottom surfaces, where the bottom surface of the integrated circuit is adapted to be positioned on the top surface of the substrate. A cover has top and bottom surfaces and an outer edge surface. The cover is adapted to be disposed over the substrate, the integrated circuit is positioned between the bottom surface of the cover and the top surface of the substrate. A removable spacer member has a definable vertical dimension positioned between the bottom surface of the cover and the top surface of the integrated circuit. A positioning member has top, bottom, and side surfaces. The side surfaces of the positioning member are situated adjacent to and affixable to, the outer edge surface of the cover; and the bottom surface of the positioning member is contactable with the top surface of the substrate. The affixable side surface of the positioning member, and the bottom surface of the affixable positioning member, are capable of maintaining a specified vertical dimension between the bottom surface of the cover and the top surface of the integrated circuit. The specified vertical dimension is defined by the vertical dimension of the removable spacer member. The bottom surface of the cover and the top surface of the integrated circuit define a gap having the specified vertical dimension when the affixable side surface of the positioning member is affixed to the outer edge surface of the cover, and the removable space member is removed. The gap is filled with a thermally conductive medium.
A related aspect of the invention provides the positioning member at least partially circumscribing the cover.
Another related aspect provides the positioning member and the cover substantially circular in shape and the positioning member circumscribing an outer surface of the perimeter of the substantially circular cover.
Yet another related aspect provides a plurality of covers that are affixable to the positioning member. In yet another aspect, the present invention provides a thermal conduction module assembly kit comprising a base being substantially planar in shape and adapted to receive on a top surface a substrate adapted to receive at least one integrated circuit having top and bottom surfaces. A cover is substantially rectangular, having top and bottom surfaces and an outer edge surface. The cover is designed to mate with the substrate such that the integrated circuit is positioned between the bottom surface of the cover and the top surface of the substrate. A removable shim member is planar in shape and has a definable vertical dimension positioned between the bottom surface of the cover and the top surface of the integrated circuit to provide a specified dimension between the top surface of the integrated circuit and the bottom surface of the cover. A positioning member has top, bottom, and inner surfaces, and is substantially circular. The inner surface of the positioning member is positioned to circumscribe and movably mate with the outside surface of the cover. The inner surface of the positioning member is affixable to the outer edge surface of the cover, and the bottom surface of the positioning member is contactable -with the top surface of the substrate. The affixable inner surface of the spacer, and the bottom surface of the affixable positioning member, are capable of maintaining the vertical dimension between the bottom surface of the cover and the top surface of the integrated circuit defined by the specified vertical dimension of the shim member, and define a gap of the same specified vertical dimension after the removable shim member is removed. The gap substantially receives a thermally conductive medium.
In yet another aspect, the present invention provides an apparatus for deploying a thermal conduction module comprising a structure defining an inner cavity. The structure includes an upper portion and a lower portion where the upper portion of the structure defines an opening. The module includes a substrate having a top and bottom surface, the bottom surface of the substrate is positioned on a top surface of the lower portion of the structure. The substrate is adapted to receive at least one integrated circuit having top and bottom surfaces, where the bottom surface of the integrated circuit is positioned on the top surface of the substrate. The module further includes a cover having top and bottom surfaces and an outer edge surface. The cover is adapted to be disposed over the substrate. The module further includes at least one positioning member. The positioning member has an inner surface being adjacent to, and affixable to the outer edge surface of the cover. The integrated circuit is positioned between the bottom surface of the cover and the top surface of the substrate. The module further includes a removable shim member having a definable vertical dimension and being positioned between the bottom surface of the cover and the top surface of the integrated circuit to provide a specified vertical dimension between the top surface of the integrated circuit and the bottom surface of the cover. An application member is positioned through the opening in the top of the structure. An actuation member is connected to the application member for lifting the application member in a substantially vertical direction. The apparatus further includes at least one adjustment element adjacent to the application member and connected to the application member so that both move synchronously. The adjustment element has a lower portion contacting an upper surface of the positioning member. The positioning member is vertically slidable by the adjustment element along the outer edge surface of the cover, such that the actuation member moves the adjustment element to position the positioning member in a desired adjacent position relating to the vertical dimension of the removable shim member.
A related aspect provides that the inner cavity is substantially circular, and the cover and the positioning member are substantially circular such that the positioning member circumscribes the outer edge of the cover.
Another related aspect provides that the inner cavity is substantially rectangular, and the cover and the positioning member are substantially rectangular such that the positioning member circumscribes the outer edge of the cover.
Yet another related aspect provides that the affixable inner edge surface of the positioning member, and the bottom surface of the affixable positioning member, are coupled to maintain the vertical dimension between the bottom surface of the cover and the top surface of the integrated circuit defined by the specified, measurable vertical dimension of the shim member. The bottom surface of the cover and the top surface of the integrated circuit defining a gap after the removable shim member is removed; and the gap has substantially the same specified, measurable vertical dimension of the shim member. The gap is substantially filled by a thermally conductive medium.
In yet another aspect, the present invention provides an apparatus for deploying a thermal conduction module assembly kit comprising a structure defining an inner cavity. The structure includes an upper portion and a lower portion, where the upper portion of the structure defines an opening. A substrate has a top and bottom surface. The bottom surface of the substrate is positioned on a top surface of the lower portion of the structure. At least one integrated circuit having top and bottom surfaces, where the bottom surface of the integrated circuit is positioned on the top surface of the substrate. A cover is substantially rectangular, and has top and bottom surfaces and an outer edge surface. The cover is adapted to be disposed over the substrate, and the integrated circuit is positioned between the bottom surface of the cover and the top surface of the substrate. A removable shim member is planar in shape and has a definable vertical dimension positioned between the bottom surface of the cover and the top surface of the integrated circuit to provide a specified dimension between the top surface of the integrated circuit and the bottom surface of the cover. An application member is positioned through the opening in the top of the structure. An actuation member is connected to the application member for lifting the application member in a substantially vertical direction. At least one adjustment element adjacent to the application member and connected to the application member so that both move synchronously, the adjustment element has a lower portion contacting at least one positioning member. The positioning member has an inner surface being adjacent to, substantially circumscribing, and affixable to the outer edge surface of the cover. The positioning member is vertically slidable by the adjustment element along the outer edge surface of the cover.
A related aspect provides that the affixable inner edge surface of the positioning member, and the bottom surface of the affixable positioning member, are coupled to maintain the vertical dimension between the bottom surface of the cover and the top surface of the integrated circuit defined by the specified, measurable vertical dimension of the shim member. The bottom surface of the cover and the top surface of the integrated circuit define a gap after the removable shim member is removed; and the gap has substantially the same specified, measurable vertical dimension of the shim member. The gap is substantially filled by a thermally conductive medium.
Another related aspect provides that the bottom portion of the structure includes a top surface defining a recess, the recess is adapted to hold the substrate.
Yet another related aspect provides at least one spring positioned between a bottom surface of the top portion of the substantially rectangular structure and the top surface of the application member. The spring providing substantially downwardly transmitting force on the application member for articulation of the application member by the actuation member, and forgivingly providing pressure to the positioning member.
Yet another related aspect provides a plurality of covers that are affixable to the positioning member.
In yet another aspect, the present invention provides a method of assembling a thermal conduction module having a base plate for holding at least one integrated circuit chip mounted on a chip substrate. A cover plate has a surface facing the chip substrate; a positioning member adjacent to the cover plate; and an application member removably fastened to the cover plate, the application member is adjustable to a predetermined distance from the cover plate or base plate. The method comprises placing a substrate on the base plate; placing at least one integrated circuit chip on the substrate; placing a removable shim member over an upper surface of the substrate and, at least one integrated circuit chip. The shim member has a thickness corresponding to a thickness sufficient to permit a thermally conductive medium to be disposed between an upper surface of the integrated circuit chip, when located on the chip substrate, and the cover plate surface facing the chip substrate, when the shim member is removed. Placing the cover plate over the shim member, the integrated circuit chip, if present, the substrate and the base plate. Adjusting the application member toward or away from the base plate, until the surface facing the chip substrate of the cover plate contacts the shim member creating a desired distance for insertion of a thermally conductive material between an upper surface of an integrated circuit chip mounted on the chip substrate and the cover plate surface facing the chip substrate. Affixing the positioning member to the cover plate. Removing the cover plate with affixed positioning member and shim member from over the substrate. Replacing the cover plate with affixed positioning member over the substrate and the base plate. Securing the cover plate with affixed positioning member to the base plate, whereby a desired gap is created for a thermally conductive medium between an upper surface of the integrated circuit and the cover plate surface facing the chip substrate, and inserting the thermally conductive material into the gap.
In yet another aspect, the present invention provides a thermal conduction module assembly kit comprising a cover having top and bottom surfaces, a structure having upper and lower surfaces, where the upper structure surface is matable with the lower surface of the cover. At least one holding element having a top surface and a bottom surface; the holding element being resiliently coupled to the structure such that the holding element is movable in a substantially vertical direction. A substrate member having an upper surface and a bottom surface. The upper surface of the substrate member being adapted to mount at least one integrated circuit, the integrated circuit having an upper surface. A base having an upper surface, the upper surface of the base is adapted for the substrate member to be positioned on the base upper surface. A removable shim element being adapted to fit over the at least one integrated circuit, and the removable shim element being positioned between the integrated circuit and the holding element; the removable shim member having a specified thickness. The removable shim element specified thickness defining the distance between the upper surface of the integrated circuit and the holding element. The holding element and the structure are couplable. The cover and the structure coupling to the substrate base such that the holding element, removable shim element and the integrated circuit mounted in the substrate member are adapted to adjust to the specified thickness of the removable shim element. The specified thickness of the removable shim element defines a specific vertical dimension between the upper surface of the integrated circuit and the holding element.
A related aspect provides that the holding element is coupled to the structure and the removable shim element is removed. The upper surface of the integrated circuit and the holding element define a gap. The gap is substantially the same as the vertical dimension of the removable shim element. The gap is substantially filled by a thermally conductive medium.
Another related aspect provides that the cap member defines at least one opening, and the opening is designed to receive the resilient element and the holding element such that the holding element is capable of substantially receding into the opening while maintaining forgiving contact with the integrated circuit.
Yet another related aspect provides that the cap member defines at least one aperture providing ventilation for the gap.
In yet another aspect, the present invention provides a thermal conduction module assembly kit comprising, a cover having top and bottom surfaces, and a structure having upper and lower surfaces. The upper structure surface is matable with the lower surface of the cover. The structure defines at least one aperture. At least one holding element having a top surface and a bottom surface, and the holding element is coupled to the structure by a resilient element such that the holding element is movable in a substantially vertical direction. The aperture of the structure is adapted to accept the holding element such that the holding element is capable of resiliently vertically adjusting within the aperture. A substrate member having an upper surface and a bottom surface, where the upper surface of the substrate member is adapted to mount at least one integrated circuit. The integrated circuit has an upper surface. The base has an upper surface, which is adapted for the substrate member to be positioned on the base upper surface. A removable shim element is adapted to fit over the integrated circuit, and the removable shim element is positioned between the integrated circuit and the holding element. The removable shim member has a defined thickness and the thickness defines the distance between the upper surface of the integrated circuit and the holding element. The holding element and the structure are couplable. The cover and the structure couple to the substrate base such that the holding element, removable shim element and the integrated circuit mounted in the substrate member are adapted to adjust to the thickness dimension of the removable shim element. The defined thickness of the removable shim element defines a specific vertical dimension between the upper surface of the integrated circuit and the holding element.
A related aspect provides that when the holding element is affixed to the structure and the removable shim element is removed; the upper surface of the integrated circuit and the holding element define a gap. The gap is substantially the same as the vertical dimension of the removable shim element. The cover is affixed to the substrate base. The gap is substantially filled by a thermally conductive medium.
Another related aspect provides that the holding structure defines at least one aperture providing ventilation of the gap.
Yet another related aspect provides that the holding structure comprises a plurality of substantially circular apertures.
Yet another related aspect provides that the cover defines at least one aperture for venting the module.
Yet another related aspect provides that the cover defines at least one aperture for venting the module, and the aperture extending through the cover a specified distance reaching the upper surface of the integrated circuit.
Yet another related aspect provides adjustment elements passing through the top cover, the structure, and the base which can provide incremental changes in the positioning of the holding elements as the holding elements contact the removable shim.